/*
 * Copyright (c) 2003, KNOPFLERFISH project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 * - Neither the name of the KNOPFLERFISH project nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.knopflerfish.bundle.http;

import java.util.Dictionary;
import java.util.Hashtable;

import javax.servlet.ServletContext;

import org.osgi.service.http.HttpContext;

import org.knopflerfish.service.log.LogRef;

public class ServletContextManager
{

  // private classes

  private final static class ContextKey
  {
    int referenceCount = 1;

    final HttpContext httpContext;

    final String realPath;

    ContextKey(HttpContext httpContext, String realPath)
    {
      this.httpContext = httpContext;
      this.realPath = realPath;
    }

    @Override
    public int hashCode()
    {
      return httpContext.hashCode() ^ realPath.hashCode();
    }

    @Override
    public boolean equals(Object object)
    {
      if (object instanceof ContextKey) {
        final ContextKey key = (ContextKey) object;
        return httpContext.equals(key.httpContext)
               && realPath.equals(key.realPath);
      }
      return false;
    }
  }

  // private fields

  private final Dictionary<ServletContextImpl, ContextKey> keyMap =
    new Hashtable<ServletContextImpl, ContextKey>();

  private final Dictionary<ContextKey, ServletContextImpl> contextMap =
    new Hashtable<ContextKey, ServletContextImpl>();

  private final HttpConfig httpConfig;

  private final LogRef log;

  private final Registrations registrations;

  // constructors

  public ServletContextManager(final HttpConfig httpConfig, final LogRef log,
                               final Registrations registrations)
  {

    this.httpConfig = httpConfig;
    this.log = log;
    this.registrations = registrations;
  }

  // public methods

  public synchronized ServletContext getServletContext(final HttpContext httpContext,
                                                       String realPath)
  {

    if (realPath == null) {
      realPath = "";
    }

    final ContextKey key = new ContextKey(httpContext, realPath);
    ServletContextImpl context = contextMap.get(key);
    if (context == null) {
      context =
        new ServletContextImpl(httpContext, realPath, httpConfig, log,
                               registrations);
      keyMap.put(context, key);
      contextMap.put(key, context);
    } else {
      keyMap.get(context).referenceCount++;
    }

    return context;
  }

  public synchronized void ungetServletContext(ServletContext context)
  {

    final ContextKey key = keyMap.get(context);
    if (key != null && --key.referenceCount <= 0) {
      contextMap.remove(key);
      keyMap.remove(context);
    }
  }

} // ServletContextManager
